The present application relates to an optical recording medium. Specifically, it relates to an optical recording medium having a light transmission layer made of a UV-curable resin and also to a method for producing the optical recording medium.
Optical recording media with increased density have been developed, and high-density optical discs having remarkably larger capacity than usual CDs (Compact Discs) and DVDs (Digital Versatile Discs), for example, are known.
In a high-density optical disc, an information signal portion for recording and/or reproducing an information signal is formed on one principal surface of the disc substrate, and a reflection film is formed on the information signal portion. Further, a light transmission layer and a protective layer are formed thereon by spin coating, for example. At the time of recording/reproduction, a laser beam is applied through the light transmission layer to the information signal portion, whereby recording or reproduction is performed.
Such a high-density optical disc has the light transmission layer, which is made of a resin curable by an activation energy beam, only on one side thereof (information-output side where a laser beam enters), and thus is asymmetric in the disc thickness direction. Due to this structure, as compared with DVDs and the like, high-density optical discs are more prone to warping.
In order to solve the problem of warping of high-density optical discs, various techniques have been proposed. For example, JP-A-2009-009638 (Patent Document 1) proposes an optical recording medium including a light transmission layer with the difference in tensile elastic modulus between −20° C. and 25° C. being 1400 MPa or less.